JP2015207877A - Radio communication system, communication device and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system capable of selecting a modulation system according to communication quality required for individual data and further improving communication performance, and a radio communication method.SOLUTION: In a radio communication system 100 which includes: a transmission side communication device which performs radio communication using an adaptive modulation system; and a reception side communication device (a radio terminal 110 and a base station 120), the transmission side communication device sets a plurality of modulation systems having different communication quality, and transmits a request for a plurality of set modulation systems to the reception side communication device. The reception side communication device selects a modulation system from among the plurality of modulation systems requested from the transmission side communication device, according to a data type for transmission.

Description

  The present invention relates to a radio communication system including a transmission side communication apparatus and a reception side communication apparatus that perform radio communication using an adaptive modulation scheme, a communication apparatus that constitutes such a radio communication system, and a radio communication method in the radio communication apparatus.

  In recent years, in wireless communication between a base station and a terminal, an adaptive modulation scheme that improves a communication speed by adaptively changing a modulation scheme according to a change in a communication environment while maintaining communication quality has been adopted. In the adaptive modulation scheme, BPSK (Binary Phase Shift Keying), QPSK (Quadrature PSK), 16QAM (Quadrature Amplitude Modulation), 64QAM, and the like are used in order from the lowest bit rate.

  In the adaptive modulation method, a communication environment is estimated based on a signal to interference and noise ratio (SINR) of a received signal and a bit error rate, that is, radio wave intensity and signal quality. Then, a modulation scheme having a higher communication rate is selected under a better communication environment, and a modulation scheme having a lower communication rate is selected under a poor communication environment. As a result, stable wireless communication can be performed between the base station and the terminal.

  Also, for example, in Patent Document 1, based on channel quality information from a receiving unit, a modulation scheme that satisfies a certain communication quality with the channel quality and has the highest transmission rate is determined as a first modulation scheme, and transmission data traffic Modulation method control that determines the modulation method with the lowest transmission rate that can transmit the amount as the second modulation method, and selects the lower one of the first modulation method and the second modulation method as the transmission modulation method A method is disclosed. According to Patent Literature 1, it is possible to reduce power consumption while maintaining communication quality by determining a modulation method in consideration of a traffic amount of transmission data in addition to a propagation path condition.

JP 2006-165939 A

  As described above, in the conventional wireless communication system, the modulation method is determined by the radio wave intensity and the signal quality. However, in wireless communication, the communication rate is not the highest priority for all data transmitted and received. That is, the communication quality to be prioritized differs depending on the data, such as data requiring a high communication rate and data requiring an error rate lower than the communication rate. However, the conventional wireless communication system cannot meet such a demand, and further improvement has been demanded.

  Furthermore, it is conceivable to select a modulation method according to the type of data to be transmitted as QoS control. However, only the transmitting side can identify the type of data to be transmitted. If the modulation method is freely selected, the receiving side communication device may not be able to demodulate. If only the lowest error rate is obtained and the lowest communication rate is preferentially selected, the communication speed is extremely lowered and the efficiency is poor.

  In view of such a problem, the present invention can select a modulation scheme according to communication quality required for individual data, and can further improve communication performance. It is another object of the present invention to provide a wireless communication method.

  In order to solve the above problems, a typical configuration of a radio communication system according to the present invention is a radio communication system including a transmission side communication apparatus and a reception side communication apparatus that perform radio communication using an adaptive modulation scheme. The communication apparatus sets a plurality of modulation schemes having different communication qualities, transmits a request for the set plurality of modulation schemes to the reception-side communication apparatus, and the reception-side communication apparatus transmits the plurality of modulation requests requested from the transmission-side communication apparatus. The method is characterized in that the modulation method is selected according to the type of data to be transmitted.

  The data type may be voice communication or data communication.

  In order to solve the above problems, a typical configuration of a communication apparatus according to the present invention is to set a plurality of modulation schemes having different communication qualities in a communication apparatus that performs wireless communication using an adaptive modulation scheme. A request for a modulation method is transmitted to a communication apparatus as a communication destination.

  In order to solve the above-described problem, another configuration of a communication device according to the present invention is a communication device that performs wireless communication using an adaptive modulation scheme, and a plurality of modulations having different communication qualities set in a communication device that is a communication destination. The method is characterized in that the modulation method is selected according to the type of data to be transmitted.

  In order to solve the above problems, a representative configuration of a radio communication method according to the present invention is a radio communication method performed by a transmission side communication device and a reception side communication device using an adaptive modulation method. Set multiple modulation methods with different communication qualities, send requests for the set modulation methods to the receiving communication device, and the receiving communication device transmits from the multiple modulation methods requested by the sending communication device. The modulation method is selected according to the data type to be performed.

  According to the present invention, there is provided a radio communication system, a radio communication system, and a radio communication method capable of selecting a modulation scheme according to communication quality required for individual data and further improving communication performance. Can be provided.

It is a figure which illustrates schematic structure of the radio | wireless communications system concerning this embodiment. FIG. 2 is a functional block diagram illustrating configurations of a wireless terminal and a base station illustrated in FIG. It is a sequence diagram explaining the radio | wireless communication method concerning this embodiment. It is a figure which illustrates the modulation switching threshold value table memorize | stored in the memory | storage part.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific numerical values and the like shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram illustrating a schematic configuration of a wireless communication system 100 according to the present embodiment. 2 is a functional block diagram illustrating the configuration of the wireless terminal 110 and the base station 120 shown in FIG. 1, FIG. 2 (a) is a functional block diagram of the wireless terminal 110, and FIG. 2 (b) is a base station. 120 is a functional block diagram of 120. FIG. In the present embodiment, while detailing the radio communication system 100 shown in FIG. 1, a radio terminal 110 and a base station that are communication apparatuses (transmission side communication apparatus and reception side communication apparatus) constituting the radio communication system 100 120 and their wireless communication methods will also be described.

  As shown in FIG. 1, a wireless communication system 100 according to the present embodiment includes a transmission side communication device that performs wireless communication using an adaptive modulation scheme, a wireless terminal 110 that is a reception side communication device, and a base station 120. Is done. In this embodiment, when data is transmitted from the wireless terminal 110 to the base station 120, the wireless terminal 110 is a transmission side communication device, and the base station 120 is a reception side communication device. On the other hand, when data is transmitted from the base station 120 to the wireless terminal 110, the base station 120 is a transmitting communication device and the wireless terminal 110 is a receiving communication device. In the present embodiment, the wireless terminal 110 and the base station 120 are illustrated and described as communication apparatuses, but the present invention is not limited to this. The present invention can also be applied to a case where wireless communication is performed using an applied modulation method in a communication device other than the wireless terminal 110 or the base station 120.

  As shown in FIG. 2A, the wireless terminal 110 includes a terminal control unit 112, a terminal wireless communication unit 114, and a storage unit 116. The terminal control unit 112 manages and controls the entire wireless terminal 110 by a semiconductor integrated circuit (not shown) including a central processing unit (CPU). The terminal radio communication unit 114 performs radio communication (radio signal transmission / reception) with the base station 120 using the adaptive modulation scheme via the terminal communication antenna 114a. The storage unit 116 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like, and stores a program processed by the terminal control unit 112 and a modulation switching value table to be described later.

  As shown in FIG. 2B, the base station 120 includes a base station control unit 122, a base station radio communication unit 124, and a storage unit 126. The base station control unit 122 manages and controls the entire base station 120 in the same manner as the terminal control unit 112 of the wireless terminal 110. The base station radio communication unit 124 performs radio communication (radio signal transmission / reception) with the radio terminal 110 using the adaptive modulation method via the base station communication antenna 124a. Similarly to the storage unit 116 of the wireless terminal 110, the storage unit 126 also stores a program processed by the terminal control unit 112 and a modulation switching value table described later.

  In this embodiment, as will be described in detail later, the terminal control unit 112 and the base station control unit 122 function as modulation scheme setting selection units 112a and 122a, respectively. When the own station (wireless terminal 110 or base station 120) is a transmission-side communication device, the modulation scheme setting selectors 112a and 122a set a plurality of modulation schemes having different communication qualities, and set the plurality of modulation schemes set. It transmits to the communication apparatus (receiving side communication apparatus) of the communication destination. On the other hand, when the local station (wireless terminal 110 or base station 120) is the receiving communication device, the modulation scheme setting selection units 112a and 122a are configured to have a plurality of communication devices (transmitting communication devices) set in the communication destination. From the modulation scheme, a modulation scheme that satisfies communication quality according to the data type is selected. As a plurality of modulation schemes having different communication qualities, a quality priority modulation scheme (relatively low value modulation) and a speed priority modulation scheme (relatively high value modulation) are respectively set.

  The data type can exemplify voice communication and data communication. In voice communication such as a voice call, since real-time characteristics are regarded as important, quality for errors (low error rate) is required rather than communication speed. On the other hand, in data communication such as browsing and mail transmission / reception, since the amount of data is large, the communication speed is required rather than the quality against errors. That is, a quality-priority modulation method with a low error rate is selected for voice communication, and a speed-priority modulation method is selected for data communication.

  FIG. 3 is a sequence diagram illustrating the wireless communication method according to the present embodiment. As shown in FIG. 3, in the wireless communication method according to the present embodiment, the wireless terminal 110 and the base station 120 negotiate at the start of communication (step S202), and set a plurality of target communication qualities. As described above, since a low error rate is required in voice communication, the target value of FER is set to 1.0%, for example. On the other hand, in data communication, since the communication speed has priority over the error rate, the target value of FER is set to 5.0%.

  FIG. 4 is a diagram illustrating a modulation switching threshold table stored in the storage units 116 and 126. In the modulation switching threshold table of FIG. 4, the vertical axis is a value (switching value) representing the signal quality calculated from the received signal, and the smaller the value, the better the quality. The horizontal axis represents the target communication quality, and the smaller the value, the less the occurrence of errors and the better the quality. In FIG. 4, the lower the target communication quality value and the smaller the switching value (the better the state), the higher the modulation method. That is, if the radio wave condition is good, the modulation can be performed at a high value, but if the communication quality is to be increased, the modulation must be performed at a low value.

  In the negotiation in step S202, the wireless terminal 110 and the base station 120 first determine a communication quality targeted for wireless communication. As shown in FIG. 4, in the present embodiment, a frame error rate (hereinafter referred to as FER) is exemplified as a communication quality parameter, and the communication quality corresponding to each of voice communication and data communication, which are data types, is satisfied. Determine the FER.

  Then, the wireless terminal 110 and the base station 120 each calculate a switching value from a wireless signal (received signal) received from the other, refer to the modulation switching threshold table, and calculate the switching value and target communication quality. The modulation method is set by (FER). Since there are a plurality of target communication qualities here, a plurality of modulation schemes are set.

  In calculating the switching value, for example, it is possible to exemplify a calculation method such as calculating the value by adding the demodulation accuracy of the received signal to the demodulation accuracy of the received signal or the demodulation accuracy of the past received signal. . Hereinafter, the modulation method giving priority to speed (required at the time of data communication) is called MR1, and the modulation method giving priority to quality (required at the time of voice communication) is called MR2. A modulation scheme used when the transmitting communication apparatus transmits data to the receiving communication apparatus is referred to as MI. These MI, MR1, and MR2 are symbols included in the head part of the payload (data area) of the transmission packet.

  When transmitting data (radio signal) from the base station 120 after the negotiation in step S202, the base station control unit 122 functions as the modulation scheme setting selection unit 122a in the base station 120 that is the transmission side communication device. Then, the modulation scheme setting selection unit 122a calculates a switching value from the radio signal received when the negotiation is performed in step S202, and sets the modulation scheme with reference to the modulation switching threshold table stored in the storage unit 126. To do.

  For example, when the switching value is 24, the modulation scheme setting selection unit 122a sets both MR1 and MR2 to 16QAM as a plurality of modulation schemes. Then, the modulation scheme setting selection unit 122a adds the set plurality of modulation schemes MR1 and MR2 to the radio signal as a modulation scheme requested to the radio terminal 110 that is the receiving communication device. Then, the base station control unit 122 of the base station 120 determines the type of data that the local station transmits to the wireless terminal 110, and determines the modulation scheme (MI) for transmitting this data. In the present embodiment, voice communication is exemplified as the data type. Then, the base station 120 transmits voice data to the wireless terminal 110 using 16QAM (MI), which is a voice communication modulation scheme when the switching value is 24 (step S204).

  In the present embodiment, the data transmission after the negotiation in step S202 is started from the base station 120. However, the present invention is not limited to this, and may be started from the wireless terminal 110. In the above example, the transmission side communication device (base station 120) determines the switching value and determines MI, MR1, and MR2 in the first data transmission after the negotiation, but the present invention is not limited to this. That is, in the first data transmission started after the negotiation, the predetermined modulation scheme may be set to MI, MR1, MR2 (for example, all set to 16QAM) without determining the switching value.

  When receiving the data (wireless signal) transmitted in step S204, the wireless terminal 110 that is the receiving-side communication device demodulates the data with reference to the MI, and a plurality of modulations added to the received wireless signal. Refer to the systems MR1 and MR2.

  Terminal control section 112 functions as modulation scheme setting selection section 112a, and selects a modulation scheme (MI) to be used when the own station next transmits to base station 120 from a plurality of modulation schemes MR1 and MR2. To do. Here, the modulation scheme setting selection unit 112a selects a modulation scheme that satisfies communication quality according to the type of data to be transmitted. If the type of data to be transmitted to base station 120 is voice communication, modulation scheme setting selection section 112a selects 16QAM (MR2) as the next transmission modulation scheme (MI) from among the plurality of modulation schemes MR1 and MR2. If the data type is data communication, MR1 is selected.

  When receiving data from the base station 120, the wireless terminal 110 that was the receiving communication device becomes the transmitting communication device when transmitting data to the base station 120 next time. Therefore, the modulation scheme setting selection unit 112a requests the base station 120 for a modulation scheme to be used when the base station 120 next transmits data to the wireless terminal 110. The modulation scheme setting selection unit 112a calculates a switching value from the radio signal at the time of data reception in step S204. For example, if the switching value is 22, the modulation scheme setting selection unit 112a refers to the modulation switching value table stored in the storage unit 116, and sets MR1 to 32QAM and MR2 to 16QAM. Then, the modulation scheme setting selection unit 112a adds the set modulation schemes MR1 and MR2 to the radio signal and transmits them to the base station 120 (step S206).

  When the radio signal transmitted from the radio terminal 110 is received in step S206, the base station 120 as the receiving side communication device demodulates this data with reference to the MI. Further, the modulation scheme setting selection unit 122a refers to the plurality of modulation schemes MR1 and MR2 added to the radio signal, and selects the modulation scheme (MI) to be transmitted next to the radio terminal 110 by the own station. At this time, when the data type to be transmitted next to the wireless terminal 110 is voice communication, the modulation scheme setting selection unit 122a selects MR2 (16QAM).

  Subsequently, the modulation scheme setting selection unit 122a calculates a switching value from the radio signal received at the time of data reception in step S206. At this time, if the switching value is 16, for example, the modulation scheme setting selection unit 122a refers to the modulation switching value table and sets MR1 and MR2 to 32QAM as the modulation scheme requested of the radio terminal 110. Then, the modulation scheme setting selection unit 122a adds the plurality of modulation schemes MR1 and MR2 to the radio signal, and transmits the radio signal to the radio terminal 110 with 16QAM (step S208).

  When receiving the wireless signal transmitted from the base station 120 in step S208, the wireless terminal 110 demodulates this data with reference to MI (16QAM). The modulation scheme setting selection unit 112a transmits the next modulation scheme (MI) to the base station 120 out of the plurality of modulation schemes MR1 and MR2, which are added in the same manner as when the radio signal is received in step S204. Select. If the type of data to be transmitted to base station 120 is data communication, modulation scheme setting selection section 112a selects MR1 (32QAM) as the next transmission modulation scheme (MI) from among the plurality of modulation schemes MR1 and MR2.

  Then, modulation scheme setting selector 112a calculates a switching value from the radio signal. For example, if the switching value is 19 at this time, the modulation scheme setting selection unit 112a sets MR1 to 32QAM and MR2 to 16QAM as modulation schemes to be added to the radio signal transmitted to the base station 120, and adds them to the radio signal. . Thereafter, the wireless terminal 110 and the base station 120 repeat the above-described operation.

  As described above, according to the wireless communication system 100 according to the present embodiment, the wireless terminal 110 and the base station 120 which are communication devices included in the wireless communication system, and the wireless communication method, the wireless communication between the wireless terminal 110 and the base station 120 is performed. In addition to the radio wave intensity and signal quality conventionally used for determining the modulation method, the modulation method based on the data type can be selected. As a result, the communication quality required according to the data type can be suitably ensured, so that the communication performance can be further improved.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  The present invention is used in a radio communication system including a transmission side communication apparatus and a reception side communication apparatus that perform radio communication using an adaptive modulation method, a communication apparatus that constitutes such a radio communication system, and a radio communication method in the radio communication apparatus can do.

DESCRIPTION OF SYMBOLS 100 ... Wireless communication system, 110 ... Wireless terminal, 112 ... Terminal control part, 112a ... Modulation system setting selection part, 114 ... Terminal wireless communication part, 114a ... Terminal communication antenna, 116 ... Storage part, 120 ... Base station, 122 ... Base station control unit, 122a ... modulation scheme setting selection unit, 124 ... base station radio communication unit, 124a ... base station communication antenna, 126 ... storage unit

Claims (5)

In a wireless communication system including a transmission side communication device and a reception side communication device that perform wireless communication using an adaptive modulation scheme,
The transmission side communication device sets a plurality of modulation schemes having different communication qualities, transmits a request for the set plurality of modulation schemes to the reception side communication device,
The wireless communication system, wherein the receiving communication device selects a modulation method from a plurality of modulation methods requested by the transmitting communication device according to a data type to be transmitted.   The communication system according to claim 1, wherein the data type is voice communication or data communication. In a communication device that performs wireless communication using an adaptive modulation method,
A communication apparatus, wherein a plurality of modulation schemes having different communication qualities are set, and requests for the plurality of modulation schemes set are transmitted to a communication apparatus as a communication destination. In a communication device that performs wireless communication using an adaptive modulation method,
A communication apparatus, wherein a modulation system is selected according to a data type to be transmitted from a plurality of modulation systems having different communication qualities set in a communication apparatus as a communication destination. In a wireless communication method performed by a transmission-side communication apparatus and a reception-side communication apparatus using an adaptive modulation method,
The transmission side communication device sets a plurality of modulation schemes having different communication qualities, transmits a request for the set plurality of modulation schemes to the reception side communication device,
The wireless communication method according to claim 1, wherein the reception side communication device selects a modulation method from a plurality of modulation methods requested by the transmission side communication device according to a data type to be transmitted.

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